Losing Boost while accelerating ! *Help* - Honda Prelude Forum

1PreLude2NV · 10-14-2001, 06:36 AM

This just started a few days ago after i had my JRSC installed for about a weeek and half. When i first got the car after the install i was Boosting 7 psi and when VTEC would hit my boost went down to 6 psi in ALL gears...... Week and a half later.... I run the car hard in first gear and boost level goes to 6 psi and drops fast to 5 psi then VTEC hits boost drops to 4 psi and seems like it may have gone to 3 psi around 8k rpms

Shift to second, Boost goes to 6 psi and drops down to about 4 psi, shift to 3rd gear boost stays at 6 psi and does not go down same as 4th gear

...... If im driving on a roll already about 50 mph i down shift to 3rd gear .. boost goes to 7 psi ...VTEC hits and goes to 6 psi ..like it should.

Do i have a Vacum leak some where ? Why would my boost levels do that in first and second gear and not in 3rd and 4th?? it used to not do that when i first got my car back after the install.

My boost level droping while accelerating mean that i am actually losing horsepower? I have read a few threads here saying that, seeing More boost(like 10 psi) on a 6 psi pulley does not actually yeild more Horespower. Its because their are some rescritions in the engine not letting all the air through thus building up the boost.

Any Input would be greatly appreciated

Thanks

iranman · 10-14-2001, 01:27 PM

Tighten up your belts--they're slipping. Don't go to high rpms either until you do, unless you want to wear out the grooves of the belt even faster. Make sure you don't have any engine fluids leaking on the belt drive system either.

Now, the reason why it'll do it in 1st & 2nd, but not third involves elementary physics/common sense. Relate it to wheelspin: the reason the tires slips in first gear is simple: the rate of acceleration of the wheel/tire is greater than the frictional force that allows the tire to 'grip' the ground. Why is it that you can't get wheel at WOT in third gear? The same applies to belts & pulleys.

Btw, this EXACT same thing (down to the pressure #'s) happened to me. That's why I only made 186WHP on my first dyno trip.

If you wish to confirm this, put the car in neutral and rev the engine until ~6.5K. That screeching sound you hear is the belt slipping. To find out which belt it is, tighten up the S/C belt a lot first, and see if the slipping occurs. If it doesn't, you know it's the S/C belt. If it still occurs, tighten up the Alt-A/C belt until it stops, then loosen up the S/C belt back to the normal tension. Do a couple quick redline runs to confirm. Presto.

1PreLude2NV · 10-14-2001, 01:53 PM

Thanks Iranman !! **Bows down to the all mighty JRSC Lude Info/guide God*

your help is greatly apprecaited... im going to go hit the Dyno on Saturday on 10-20-01 and ill post my dyno sheet up as well. Thanks for the tip on reminding to get an Air/Fuel Graph as well !!

1PreLude2NV · 10-14-2001, 01:56 PM

o yeah forgot to mention..... i am losing boost in 3rd and 4th gear now as well.... Max i hit now is 6 psi and goes down to 5 psi at VTEC and close to 4 psi.. im seeing it in all gears now... Thanks Iranman